[IMP] project: Don't display stages if project is not set

Purpose
=======

If the user creates a task and if the project isn't set, then all the
stages that are not linked to a project are displayed, which is polluting
the form view.

Specifications
==============

If no project is set on the task form view, do not display any stages
in the statusbar.

closes odoo/odoo#40041

Signed-off-by: Yannick Tivisse (yti) <yti@odoo.com>

addons/project/views/project_views.xml

@@ -442,7 +442,7 @@
                     <header>
                         <button name="action_assign_to_me" string="Assign to Me" type="object" class="oe_highlight"
                             attrs="{'invisible' : [('user_id', '!=', False)]}"/>
-                        <field name="stage_id" widget="statusbar" options="{'clickable': '1', 'fold_field': 'fold'}"/>
+                        <field name="stage_id" widget="statusbar" options="{'clickable': '1', 'fold_field': 'fold'}" attrs="{'invisible': [('project_id', '=', False)]}"/>
                     </header>
                     <sheet string="Task">
                     <div class="oe_button_box" name="button_box">